Air filter element with a control tube and divided housing

ABSTRACT

An air filter element, in particular for the cleaning of combustion air for internal combustion engines, in air filters with a substantially cylindrical, air-permeable housing. The air filter element has a raw air inlet area (2) and a clean air outlet area (3). The clean air outlet area is arranged substantially concentrically on one of the end surfaces of the cylindrical housing (1), and the raw air inlet area occurs substantially across the surface of the housing (1). An air-permeable center tube (4) connecting to the clean air outlet area extends inside the housing (1), and a substantially metal-free filter insert (5) is slid over the center tube (4) and separates the clean air from the raw air side. The opposite end surface (7) of the insert is sealed, and the clean air outlet side of the housing (1) has an axial seal (8) on the face thereof, it being possible to divide the housing (1).

The invention relates to an air filter element, especially for cleaningcombustion air for internal combustion engines in air filters.

Such air filter elements are known, for example due to their use incommercial vehicles, especially in dusty country.

Air filter elements known heretofore are replaced after a certain timeof operation. Depending on the amount of dust, the useful life of an airfilter can amount to a few days or as much as several months. Usually,known filter inserts consist of a combination of materials, sheet steelbeing used especially for the supporting tubes. The actual filter mediumis paper or synthetic fleece which in itself is not able to withstandthe forces caused by pulsation in internal combustion engines. Disposalof such air filter elements by separating them into their componentsentails great effort and is therefore uneconomical and expensive.

According to the "Technische Anleitung Abfall" [technical guidelines onwastes] governing waste disposal in the Federal Republic of Germany, thereduction of waste takes priority over waste recycling and disposal. Inwaste recycling it is required that recycling be technically possible,the cost of the recycling be reasonable, and that a market exist or canbe created for the materials or energy. Until these criteria aresatisfied the wastes must be properly disposed of.

In the case of air filter elements, recycling has been difficult onaccount of the disadvantages described.

The invention is thus addressed to the problem of improving an airfilter element of the kind described above such that the use ofessentially metal-free filter inserts, which do not have to be suitablefor withstanding forces, will be possible in connection with therecycling of the rest of its parts.

This problem is solved according to the invention in that thecylindrical housing of the air filter element is permeable to air, theair filter element has a raw air inlet 2 and a clean air outlet 3, theclean air outlet is substantially concentric with one of the ends of thecylindrical housing and the raw air admission occurs substantiallythrough the mantle surface of the housing, while a central air tubeextends in the interior of the housing and communicates with the cleanair outlet. An essentially metal-free filter insert is inserted throughthe center tube which separates the clean air side from the raw airside, its opposite end being closed; the clean air outlet end of thehousing has an axial gasket on top of it, and the housing is divisible.

An advantageous embodiment provides for the central tube to be joined toone half of the housing. Installation and removal is facilitated by thisone-piece construction. The operation of placing the filter insert onthe central tube followed by installation in the housing is simplified,since it is no longer necessary to center the filter insert.

Another advantageous embodiment provides for the filter insert to bereleasably joined to the central tube. This has the advantage, for onething, that when the used-up filter insert is disposed of, only theinsert needs to be replaced, which shifts the use of materials to thereplacement part side. On the other hand, this also reduces the amountof material to be disposed of. The result is a replacement part that is,for example, metal-free.

Another advantageous embodiment provides for the end of the filterinsert facing the clean air outlet to be given a sealing bead, thesealing bead being sealingly in contact with the surface of the centraltube and forming a radial seal. Upon insertion into the housing thefilter insert comes automatically into the correct installed positiondue to the axially tolerant seal to the central tube. Furthermore, thiseasily flexible design of the filter insert is capable of absorbing anyshock pressures without damage.

In another advantageous embodiment provision is made for the end of thefilter insert facing the clean air outlet to be given a sealing bead,the bead being in sealing contact with the end of the housing half andforming an axial seal. Due to the special configuration of the seal, sothat it can assume axial sealing properties if the length of the filterinsert is correct, the assurance is given that in case of a shockpressure the filtering properties remain intact.

Another advantageous embodiment provides a safety cartridge within thecentral tube, with its end opposite the clean air outlet closed andreleasably joined to the central tube. This safety cartridge providessafe filter operation; its releasability, as in the case of the filterinsert, allows easier handling as regards insertion and disposal.

Another advantageous embodiment provides for the filter insert toconsist of a pleated paper or nonwoven material and for the end platesas well as the sealing bead to be made of PUR foam. This combination ofmaterials has advantages in case of shock pressures such that no damagewill be done to the filter insert.

One advantageous embodiment provides that the air filter element befastened by a snap-fastening means capable of binding the housing halvestogether and connected to the cover or housing by a film hinge or metalhinge. By means of this the housing parts can be fastened togetherquickly and easily.

In another advantageous embodiment the parts of the air filter elementthat do not belong to the filter insert are reusable. On account of thisreusability of the peripheral parts the life of the product is increasedand the amount of waste is thus reduced.

Another advantageous embodiment provides that the reusable parts consistof metal and/or plastic. This has the advantage that even in the eventthese peripheral parts are recycled they will be in the same class, andboth substances are relatively easy to reuse.

Another advantageous embodiment provides for a hand guard. This handguard made, for example, of slotted plastic, prevents damage to thefilter insert when it is installed.

Another advantageous embodiment provides for the end of the filterinsert remote from the clean air end to have tolerance lips by means ofwhich a secure seating in the housing is assured. The tolerance lippermits, within its geometric possibilities, a certain axialequalization and provides for a certain pressing of the end of thefilter insert against the central tube.

In an additional advantageous embodiment there exists an air filterwhich contains an air filter element according to one or more of theabove-stated claims. In this embodiment an air filter element describedabove is urged with its clean air outlet against a sealing surface ofthe air filter containing a clean air outlet, e.g., by means of a snaplever. The longitudinal forces thus produced are taken up by the housingof the air filter element. The central tube in the housing absorbs anytransverse forces that occur, so that the filter element is mounted inthe housing of the air filter element alnost without the application ofany force.

These and other features of preferred embodiments of the invention willbe found not only in the claims but also in the description and thedrawings, it being possible for the individual features to be realizedindividually or together in the form of sub-combinations in theembodiment of the invention and in other fields, and can be advantageousas well as independently patentable embodiments for which protection ishereby claimed.

Embodiments of the invention are represented in the drawings and areexplained herewith.

The drawings show:

FIG. 1 an air filter element,

FIG. 2 a carrying and installation handle on the air filter element,

FIG. 3 a maintenance interval unit.

The air filter element consists of a housing 1 which is divisible intotwo parts. The housing 1 is permeable to air, for example through theholes made on the circumference which constitute the raw air inlet 2.The clean air outlet 3 is integrated in the housing half 9. In theinterior of the housing 1 is a likewise air-permeable central tube 4which is connected to the clean air outlet 3. This junction can becemented, welded, screwed or snapped together.

A metal-free filter insert 5 of pleated paper is slipped over thecentral tube 4. With PUR gaskets on the ends of the filter insert 5 thefilter insert separates the clean air side from the raw air side. On theend facing away from the clean air side a PUR gasket extends over theentire end face and serves not only for sealing but also for the axiallytolerant fixation of the filter insert 5 in the housing 1. In thehousing half 9 there is an axial gasket 8 for sealing contact with theair filter. The filter insert 5, which is seated removably on thecentral tube 4, has a hand guard, preferably of slitted plastic, drawnover its outer surface. In less rough use this can be omitted.

For easier installation and removal and for the secure and leak-proofoperation of the air filter element, the filter insert has a radiallyacting seal 6 which guarantee this in connection with end 7 andtolerance lips 10.

In one embodiment the two housing halves are screwed together, but abayonet or snap fastening or a hook fastening is conceivable. As shownin FIG. 2, a handle is fastened to the air filter element, by means ofwhich the air filter element is easier to manipulate, especially when itis inserted into the air filter, when the air filter element is held bythe handle against the sealing surface of the air filter containing aclean air outlet, until the housing of the filter element is fixed inplace with a quick acting lever, for example, which is not shown.

In one embodiment a maintenance indicator is represented, as it can beseen in FIG. 3, by means of which the maintenance interval can be read,for the manufacturing and sale date indicated thereon, for example. Onthe basis of the dust loading related to specific use in relation torunning time, it is possible to make a prediction concerning thepossible dust loading in proportion to the time the filter element hasbeen in the air filter.

In an alternative embodiment the air filter element is provided with acatch means which can join the housing halves together and is connectedto the cover or housing by a film hinge or a pinned hinge.

In an additional alternative embodiment a safety cartridge is heldwithin the central tube, which is provided additionally in order toprevent contamination while the filter insert is being changed; it isclosed at its end opposite the clean air outlet and is removablyconnected to the central tube. A hand guard is provided or slipped overthe periphery of the filter insert and can consist of slitted plasticfilm.

What is claimed is:
 1. An air filter element comprising a substantiallycylindrical housing having an air-permeable circumferential surfacedefining a raw air inlet through which unfiltered air is admitted to thefilter element and a clean air outlet disposed substantially coaxiallyon a first axial end of the cylindrical housing, an air-permeablecentral tube communicating with the clean air outlet and extending intothe interior of the housing, a substantially metal-free filter insertslid over said central tube, said filter insert separating an annularraw unfiltered air space from a central clean air space, a second axialend of said filter element being closed; and an axial gasket at saidfirst axial end of said housing; said housing further comprising firstand second axially alianed housing parts.
 2. An air filter elementaccording to claim 1, wherein said central tube is joined to one of saidfirst and second housing parts.
 3. An air filter element according toclaim 1, wherein said filter insert is releasably affixed to saidcentral tube.
 4. An air filter element according to claim 1, wherein anend of the filter insert facing said clean air outlet is provided with asealing bead in sealing contact with and forming a radial seal with anouter circumferential surface of said central tube.
 5. An air filterelement according to claim 1, wherein an end of the filter insert facingthe clean air outlet is provided with a sealing bead in sealing contactwith and forming an axial seal with an axial end of the housing half. 6.An air filter element according to claim 1, wherein the filter insertcomprises a pleated paper or fleece cylinder and end plates and asealing bead of a polyurethane resin foam.
 7. An air filter elementaccording to claim 1, wherein the cylindrical housing, central tube, andaxial gasket are reusable.
 8. An air filter element according to claim7, wherein the reusable parts are formed of at least one materialselected from the group consisting of metals and synthetic resins.
 9. Anair filter element according to claim 1 wherein said second end of thefilter insert is provided with resilient tolerance lips.